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THE BIOSYNTHESIS OF CHOLESTEROL AND OTHER STEROLS BY BRAIN TISSUE
Author(s) -
Ramsey R. B.,
Jones J. P.,
Nicholas H. J.
Publication year - 1971
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1971.tb00011.x
Subject(s) - sterol , digitonin , microsome , desmosterol , biochemistry , cholesterol , chemistry , mevalonic acid , chromatography , biosynthesis , fraction (chemistry) , biology , enzyme
— The distribution of 14 C into several subcellular fractions of adult rat brain was studied as a function of time, following intracerebral injection of [2‐ 14 C]mevalonic acid. As expected from previous studies, the microsomal fraction was indicated as the site of sterol biosynthesis. The myelin fraction showed a marked and early uptake of I4 C‐labelled, digitonin‐precipitable material. This was assumed to be a non‐enzymic uptake of sterol intermediates. The mitochondrial fraction exhibited a rapid uptake of 14 C‐labelled, nonsaponifiable material, but a very slow accumulation of 14 C‐labelled, digitonin‐precipitable product. Examination of the nonsaponifiable 14 C‐fractions by TLC showed a rapid appearance of labelled 4‐desmethyl sterols in the microsomal fraction. The myelin fraction selectively retained 4,4′‐dimethyl sterol but seemed to release this with time, possibly to be further metabolized by the microsomes. Examination of [ 14 C]digitonin‐precipitable material by the dibromide method showed that although labelled 4‐desmethyl sterol appeared quite early, cholesterol itself was formed slowly in all fractions.